By Andrew Osborn
LONDON, March 21 (Reuters) - Media mogul Rupert Murdoch sharply criticised British Prime Minister David Cameron on Thursday for agreeing tougher press regulation, saying the new system was a "holy mess" and that Cameron had disappointed his supporters.
Cameron struck a surprise deal on Monday with his junior coalition partners, the Liberal Democrats, and the opposition Labour party, that will allow a new regulator to be set up with the powers to levy large fines on newspapers and oblige them to print prominent apologies where appropriate.
"UK holy mess with Internet unworkably included," Murdoch wrote on social media site Twitter on Thursday. "Cameron showing true colors shocking many supporters."
The Sun newspaper, which is owned by News Corp, of which Murdoch is the chairman and chief executive officer, also delivered a front-page critique on Thursday of the government's annual budget.
"Budget coverage as approved by the Ministry of Truth," it quipped, referring to the fictional Ministry of Truth in George Orwell's "1984" novel about a totalitarian state.
Cameron acted to strengthen regulation of the press following public anger over phone hacking by some tabloid newspapers, including Murdoch's now defunct News of the World, and after a judge-led inquiry showed how widespread it was.
He had previously said he didn't think it was necessary to enshrine the new system of self-regulation in law, but agreed to allow parliament to approve two amendments as part of a compromise, which he said strengthened the new system, but which press critics said undermined freedom of expression.
The system will be voluntary, but there will be strong financial incentives to encourage news media to opt into it.
Politicians from across the political spectrum backed it as did a group representing victims of newspaper phone hacking.
But some of the country's biggest press groups have signalled they are unhappy and are still considering how to respond, with some talking of a boycott, a legal challenge, or an alternative regulatory system. At least two news magazines have already said they won't be joining the new system.
British politicians have criticised Murdoch, a U.S. citizen of Australian origin, for seeking to influence politics through his still sizeable media assets in Britain. But Murdoch has shrugged that off.
Earlier this month, he had dinner with the leader of the anti-European Union UK Independence Party, a party that has become an electoral headache for Cameron ahead of a 2015 general election.
Critics said at the time he was trying to encourage dissent in Cameron's Conservative party to destabilise the prime minister, whose leadership has come under pressure from within his own party.